AC Problems

[kellyandtopher]

Ok I'm gonna start off by saying that I am female and have no clue how to work on my '94 Explorer XLT 4x4. My husband wont work on it either because it has a "brain" so it is left to me to figure out what is wrong with it without spending too much money, you know like taking it to a shop and have them overcharge me.
Well, the problem is my AC when I turn my AC on I get warm air blowing. So I have talked to some "guys" who suggested that I try to charge it, so I just did that today "bought a kit at Walmart" with the assistance from a "guy" friend. I am good on my R-134a coolent. Now, I had a "guy" say that it could be a relay, he checked it with a light tester and there was no light that came on, I dont know if I can trust it cause he had a few wires and said something that made me think that I couldnt trust it, now i was told today that the relay doesnt matter cause its WOT something or other. I do not hear the clutch click in the compressor when I turn my AC on.
Now that I have written what is wrong, what can I do now myself inexpensively. If there is anything to do.

 

[Glacier991]

Ok... and not because you are a woman, some of the best mechanics I ever knew were of the female persuasion, but for you and a zillion guys here's kind a run down on the Explorer AC.

Here's the way the system works: The compressor compresses the gaseous refrigerant into a superheated gaseous state. From there it goes to it's own "radiator"... the condensor, which causes it to give up heat and "condenses" the gas into a liquid (more or less). The liquid runs though a line, through the "orifice tube" which sort of "meters" the refrigerant into another little radiator (the evaporator inside the passenger cabin) where it expands and therefor cools (remember Boyles law from H.S Physics?). You blow air though that little radiator and voila A/C. On the other sideof the evaporator is a reservoir called the accumulator. It takes up excess refrigerant, contains a chemical that absorbs any moisture present in the system (always a bad thing) and from there the gaseous refrigerant is fed back to the compressor to begin another cycle.

Things to go wrong. Your system has a couple switches (on or near the accumulator) that are connected to the compressor clutch, and that are either on or off, depending. A low pressure switch which will NOT permit your AC compressor to run is the pressure is too low (it takes the OFF position in that case), and one which shuts it off if it is too high (on later models after 93). Why? Well the oil for the compressor is carried in the refrigerant. If there is inadequate refrigerant, no oil. No oil, compressor seizes, toast. Too high uually means something is wrong, so it's also a safety thing.

The first question to ask is, when I look at the compressor, is the pulley ALSO turning the compressor? There is a clutch on the compressor hooked up to those switches.... if you look at the center which is the AC compressor shaft, is IT turning along with the rest of the pulley? If it is, the AC is operational. Warm air in that situation is one matter with an entirely different set of issues, and fortunately not as common as what we are about to talk about. If it isn't (the usual case with your complaint) we need ask why not? 99% of the time it is because the low pressure switch is sensing a low pressure (read low refrigerant charge) situation and PROTECTING your investment. (Yes and sometimes the switch can also go bad too).

Ok how do we know? Well ideally a gauge set can be connectedd and read the refrigerant pressure. Generally a non-op compressor in that situation means almost zero charge and a leak. The more typical case is a system where the compressor clicks on, and a few seconds later goes off... only to soon go on and so on and so forth. (the click click click you hear people describe)

A totally discharged system truly SHOULD have the air removed and a state of vacuum created (as comparedd to vacuuming carpet! - in this case we are establishing a state of near perfect vaccuum within the innards of the AC system) THEN refrigerant is introduced and added up to spec and you will have a good cold operating system. BUT if it was near zero charge, you have (or had and unless fixed will have it again) a leak and unless you find it, you will be repeating the process. Leaks are best left to folks with the tools (special sniffers etc), but "you" can add dye and find SOME with a blacklight. Finding them and fixing them are two different things. Leaks. In order of prevalence 1) Compressor seal (not a DIY); 2. Accumulator rusting out (Explorer anyway); 3. Valves where you add refrigerant; 4. Everywhere else.

I'm guessing you have no AC because you have little or no refrigerant because it leaked out. Don't let anyone sell you a single part without first having the system leak tested, and come back here first. We are all happy to help. Hope this was of some help as well.

 

[kellyandtopher]

Thanks

Thanks Glacier, I appreciate the response my husband told me to take it in and get a system check on it so I will do that on Monday and see what "they" tell me. I will then return here to see if there is anything I can do that will be less expensive.

Thank You